Uk regs for  NTO 123J type registrations (ie not the new FL 09 AOL type) were originally issued by councils and the last 2 letters were designated to councils, TO, TV, AL for example were all Nottingham/Nottinghamshire ones, the first letter indicated the year first used, but these varied, and may have been used in other decades, ie FLY was used  Jan 1971 on, but also in 1963 and pre war! LK meant your bike originated like mine  in London and FLK regs issued Aug 1970 onwards. As regards "K0" in uk, have still to find anything official to say such called that, no doubt other honda's ie the CB72 altered over the years in little ways? but no difference in title? Different make of course, but the BSA  500cc "Gold Star" was always known as The Gold Star (or Goldie) however it also had official model numbers over the years stating as the M24 in 1938, by 1948 it was the YB34, ' 49 the ZB, '53 the BB, '54 the CB, '55 the DB and '56 the DBD   (all with 34 after) these were all official model types, in some cases, totally different frames or engines, bit like the CB750, K1 K6 etc? (won't even go down the Suzuki  GS1100/GSX1100EZ/GSX1100EF/EG; B&Q, M&S route etc lol)